README Written by Stu Grossman Updated 9/26/95 by Fred Fish for gdb 4.15 release Updated 4/18/97 by Martin Hunt Updated 8/15/02 by Keith Seitz This file describes how to build, install, use and hack on Insight (formerly GDBtk), a TK-based GUI for GDB, the GNU debugger. Introduction ============ Insight is a version of GDB that uses Tcl/Tk to implement a graphical user inter-face. It is a fully integrated GUI, not a separate front-end program. The interface consists of several separate windows, which use standard elements like buttons, scrollbars, entry boxes and such to create a fairly easy to use interface. Each window has a distinct content and purpose, and can be enabled or disabled individually. The windows contain things like the current source file, a disassembly of the current function, text commands (for things that aren't accessible via a button), and so forth. Building and Installing ======================= Building Insight is very straightforward. It is configured/built by default when you checkout or download Insight. Right now, Insight MUST be built using the versions of Tcl, Tk, and Itcl that come with the sources. We're working to fix that, but it is going to take a lot of time. (Want to help?) On Unix machines, you will also need to have X11 (R4/R5/R6) installed (this is a prerequisite to installing Tk). Insight inherits much of GDB's configuration options (like where it is to be installed). See the GDB README file for more details on configure options and such for GDB. It is recommended that Insight, like GDB, be built outside of the source directory in order to preserve the integrity of the source directory. This is very useful, for example, when building GDB/Insight for multiple hosts or targets. For example: host> ls src/ host> mkdir insight; cd insight host> ../src/configure host> make host> make install Environment Variables ===================== Insight and all of its support infrastructure read various environment variables for optional startup information. All of these environment variables are optional: Insight and its packages know how to find their files in both the install and the source trees. Name Description ---- ----------- TCL_LIBRARY The location of the Tcl library files TK_LIBRARY The location of the Tk library files REDHAT_GUI_LIBRARY The location of the libgui library files GDBTK_LIBRARY The location of the Insight library files INSIGHT_PLUGINS A colon-separated list of directories to search for plugins (see gdb/gdbtk/plugins/HOW-TO) GDBTK_DEBUG Controls runtime loading of the Debug Window. (This is the most useful debug option.) GDBTK_TRACE Controls runtime tracing of the tcl code GDBTK_DEBUGFILE Filename to send debug output GDBTK_TEST_RUNNING Testsuite variable. See gdb/testsuite/gdb.gdbtk/README for more information. INSIGHT_FORCE_READ_PREFERENCES If set, read .gdbtkinit (or gdb.ini on windows) even when -nx is passed to GDB. DISPLAY The display to use on unix/X platforms. Not used on Windows platforms. All of the environment variables for controlling Insight are well documented in gdb/gdbtk/library/main.tcl. Search for "env" to find them all. Using Insight ============= You can start Insight by running the `insight' executable (for cross-platform targets, include the build triple, i.e., `powerpc-elf-insight'). Alternatively start Insight by telling GDB to start it with `gdb -w' or `gdb -i=insight'. If everything goes well, you should have several windows pop up. To get going, hit the Run button, and go exploring. If you want to use GDB in command line mode, just use the -nw option or the console interpreter (`insight -i=console'). Insight comes with all your standard debugger windows, including: o Console Window o Source Window o Register Window o Memory Window o Locals Window o Watch Window o Stack Window o Thread/Process Window o Function Browser Window o Debug Window (for developers) Insight also has an extensive (if outdated) online help system which describes all the windows and explains how to use them. Users are urged to browse this help system for information on using Insight. Hacking Insight =============== The GUI is primarily implemented by Tcl/Tk code which lives in gdb/gdbtk/library and bunch of C files in gdb/gdbtk/generic. The Tcl/Tk code determines the look and feel, the layout, and the functions associated with all of the interface elements. The C code is mostly just glue between GDB internals and Tcl-land. In essence, all of the policy is implemented in Tcl/Tk, and is easily changed without recompiling. To make more serious changes to the interface, such as adding a new window or changing the framework, you will have to hack the tcl code (and probably the C code as well). The tcl library install directory is $(libdir) (probably /usr/local/lib/insight1.0). But, you will probably want to hack on your own private copy before putting it up for the rest of the users. To find the GDB tcl code, GDB first checks for the environment variable GDBTK_LIBRARY. GDB will check this directory for the file "main.tcl". If GDBTK_LIBRARY is not set, GDB will look for main.tcl in the install directory, and finally it will try to find the tcl directory in the sources. A word about the different files in Insight is in order. Insight is a hybrid of C code and "Tcl" code (actually Incr Tcl code). We use the following conventions for naming our tcl files (most of the time!). Any file with a ".tcl" extension is simply vanilla tcl code. Any file ending with ".itcl" is an Itcl file, class definition and implementation all in one. So far so good. Now comes the toughy: Files ending in ".ith" are Itcl class definition files, and they all must have a corresponding implementation file, ending in ".itb". Why do we do this? Simple. With Itcl, one can reread class implementations at runtime, but one cannot change the class definition. So all those ".itcl" files can only be reread be restarting Insight. The same is not true, though, of the ".itb" files. Those files can be changed and immediately reread and used in Insight without having to restart (as long as the class definition doesn't change). This is a nifty Itcl feature which is fully exploited by the Debug Window, which has a "ReSource" menu on it to reread the Tcl files. (To get to the Debug Window, hit Ctrl-Alt-F11 in the Source Window or type "tk ManagedWin::open DebugWin" in the Console Window.) Internally, Insight is basically GDB, linked with Tcl/Tk, some Tcl/Tk extensions, and some glue code that interfaces GDB internals to Tcl-land. This means that Insight operates as a single program, not a front-end to GDB. All GDB commands, and a great deal of the target program state are accessible to the Tcl programmer. In addition, there are many callbacks from GDB to notify Tcl-land of important events. Many of these are accomplished via "hooks" in GDB, and others are accomplished using event notifications. GDB is slowly deprecating the use of "hooks" in favor of its new event mechanism. All of the below commands have lots of nice comments before them explaining what they all do, how they are to be used, etc. The source code is the definitive authority (other than a maintainer) for the definition/usage of a command in Insight. Hackers are urged to read through the source code for any commands which may need explaining. New Tcl Commands: Here is a brief, if incomplete, summary of the Tcl commands that are created by Insight. These are installed into the Tcl interpreter in the C files. Name Description ---- ----------- gdb_cmd Sends a text command to gdb. Returns the result. DEPRECATED: Do not use any more. gdb_loc Returns a list of useful tidbits about the specified GDB linespec gdb_sourcelines Returns a list of executable lines for a source file gdb_listfiles Returns a list of all of the source files gdb_stop Stops the target process (or at least tries to) gdb_reginfo Returns information about registers (names, numbers, values, size, etc.) gdb_disassemble Returns the text of a disassembly of the entire function. No longer used. gdb_load_disassembly Loads the disassembly of a location into a source window's textbox gdb_eval Returns the value of a given expression gdb_get_breakpoint_list Returns a list of all breakpoints gdb_get_breakpoint_info Returns a list of info about a breakpoint Tcl procedures that are hooked into GDB: This is a list, albeit incomplete, of the "hook" functions that are installed into GDB. The actual "hooks" are installed/initialized in gdb/gdbtk/generic/gdbtk-hooks.c (and maybe one or two in gdbtk.c). The list below is the Tcl side of the hook. Name Description ---- ----------- gdb_tcl_fputs Sends output into Tcl for the command window gdb_tcl_query Pops up a query window gdbtk_tcl_breakpoint Notifies Tcl of changes to a breakpoint gdbtk_tcl_idle Notifies Tcl that debugged process is now idle gdbtk_tcl_busy Notifies Tcl that debugged process is now running Events: Starting with GDB 5.0, GDB has had an event loop. Although largely unused right now, with it came some useful "baggage", especially event notifications, even though they, too, were largely incomplete. The list of events continues to grow, and Insight and GDB often "share" overlapping events, but the list below is complete (since there are only a few defined events). The source for these events can be found in gdb/gdbtk/library/gdbevents.it[hb]. Name Description ---- ----------- BreakpointEvent A breakpoint has been created/modified/deleted TracepointEvent A tracepoint has been created/modified/deleted SetVariableEvent User has issued a "set" command in Console BusyEvent The debugger is "busy" IdleEvent The debugger is "idle" UpdateEvent The state of the target has changed (or the GDB's view of the target has changed) ArchChangedEvent The architecture of the system has changed (this can happen when GDB defaults to using some basic CPU and detects that a more elaborate CPU is actually being used, e.g., SH5) GDB Commands: Insight installs a few GDB commands, which are available with the Console Window. Name Description ---- ----------- tk Executes the arguments in the Insight Tcl interpreter view Displays the given linespec in the Source Window Problems ======== During building, you may run into problems with finding Tcl, Tk or X11. Look in gdb/Makefile, and fix TCL_CFLAGS, TCL, TK_CFLAGS, TK, and ENABLE_CLIBS as appropriate. If you one of the following messages when you run gdb: Tcl_Init failed: can't find init.tcl; perhaps you need to install Tcl or set your TCL_LIBRARY environment variable? or Tk_Init failed: can't find tk.tcl; perhaps you need to install Tk or set your TK_LIBRARY environment variable? then you haven't installed Tcl or TK properly. Fix the appropriate environment variable to point at the {tcl tk}/library directory, and restart gdb. Known Bugs ========== generic problems o Using the GDB commands "up"/"down"/"frame" in Console Window can cause GDB and Insight to get out of sync. If this happens, simply use the Stack Window or the frame navigation buttons on the Source Window's toolbar to resync the two. o Not really a problem, but it might be nice to have a frame/stack window that displays the last N words on the stack, along with indications about which function owns a particular frame, how the frame pointers are chained, and possibly the names of variables alongside their frame slots. host- or target-specific problems o Windows is hosed. Tk8.3 in sources.redhat.com is not stable on windows. Wanna help? Where to find help ================== The first place to turn for help is the online help system. It may be old, but it is still largely correct: it explains what everything does. If that fails, search the mailing list archives for other users who may have had similar problems or questions. The archives are online at http://sources.redhat.com/insight/mailinglist.htm . If all else fails, send a note to the mailing list, insight@sources.redhat.com, where users and maintainers lurk. This is a very low traffic list, so don't be afraid to join the list. Instructions for joining are on our homepage, http://sources.redhat.com/insight .